Large-scale Shaking Table Test On Dynamic Response Of Homogenuous Slopes Under The Effect Of Strong Earthquake

The mountainous area covers 2/3of the territorial area of our country, and earthquakes in our country are occurred frequently. Earthquake is the main factor that induces slope instability and the occurrence of secondary geological disaster such as landslides, collapses and debris flows. The 5.12 Wenchuan Earthquake in 2008 induced ten thousands of collapses and landslides. It made a huge life and property loss in disaster areas. So, studying the deformation failure mechanism and dynamic response pattern of slopes under the effect of strong earthquake has important theoretical and practical significance.On the basis of the background of earthquake and geological environment of seismic areas, large-scale shaking table model test about homogeneous rocky slope will be studied in this thesis. Experimental equipments will be induced detailedly, basic principles of designing similarity ratios of model system is provided, the similar design for the model system is done, preparation methods of model materials and structures and physical property of model materials are presented in this thesis . What's more, according to the purposes and conditions of the test, the choice and layout scheme of sensors are analyzed. The choice and loading methods of table-board input motion is elaborated on the basis of the environment of seismic areas. Deformation and failure of model on the process of test are studied, acceleration data of different operating conditions, different rocky slopes and different topographic units are analyzed. The influence of geological conditions of slopes and moving load of earthquakes on deformation and failure and the rule of dynamic response of slopes are discussed systematically. And then, the main mode and process of deformation and failure of slopes induced by strong earthquake are summarized, the dynamic response characteristic and rule of slopes are revealed. All these studies provide the reasonable explanations for numerous large-scale landslides and collapses after the Wenchuan Earthquake, provide scientific basis for analyzing the dynamic stability and structural seismic design of slopes. Through analyzing the deformation and failure and monitoring data obtained through the test, combine with the survey of deformation and failure in the seismic areas, the following rules about the dynamic response of rocky slopes are founded:1) on the aspect of the characteristic of deformation failure and genetic mechanism of slopes, the deformation failure of slopes under the effect of earthquake occurred on the middle upper of the slopes, the deformation failure of soft rock slopes is stronger than hard rock slopes. In the hard rock strata, hazards such as collapses of occurred, while, landslides often occurred on the soft rock slope. The main factors that induce the failure of slopes are the effect of unidirectional vertical earthquake wave and unidirectional horizontal earthquake wave, the increase of destructive of seismic compound wave on slopes, and horizontal seismic force. As the increase of seismic amplitude under the effect of slope models, the deformation failure of slopes is stronger. When the seismic frequency on the slopes is close to the natural frequency of slopes, the deformation failure is stronger. The longer the time of seismic wave on the slopes, the stronger the deformation failure of slopes is. The main mode of the deformation failure of rocky slopes under the effect of earthquake is: tension fracture and toppling-- Shear slip.2) On the aspect of rule of dynamic response, different acceleration data of different seismic condition are contrasted and analyzed, the geologic conditions of the slope itself and the effect laws of the speed dynamic response of rocky slopes under the effect of ground motion parameters are discussed. Through the synthetically consideration about the influence of the dynamic response of ground motion, the elevation amplification effect of slopes, the law of dynamic response of different slopes, the law of dynamic response of inside and outside slopes, law of dynamic response of different amplitude slices, frequency parameters and directions of seismic waves. It is found that: under the effect of earthquake, acceleration amplification effect of soft and hard rock slopes alternating increase. On the upper of slopes, the response acceleration of the shock excitation of unidirectional earthquake wave of soft rock slopes and the response acceleration of vertical seismic compound wave. On the bottom of slopes, the law is on the contrary. There is a horizontal magnification phenomenon of acceleration amplitude on the surface of the bottom of slopes. In a certain elevation range, the peak value of response of acceleration increases with the increase of elevation range, and the acceleration decreases when a certain elevation range received. There is a great influence of seismic amplitude on the dynamic response of slopes. The change law of peak amplitude of acceleration is nonlinear. There is no clear influence of seismic amplitude on the dynamic response distribution law on the elevation direction. There is no influence of seismic amplitude on the peak of acceleration response; the selectivity of amplification frequency of seismic waves by slopes exists. On a certain elevation range, the amplification frequency of seismic waves of the same slope under the effect of ZX-direction, Z-direction and X-direction decrease successively, horizontal dynamic response seismic compound wave is stronger than vertical. In the mean time, those laws are also influenced by ground motion parameter and geological conditions of slopes. Under the effect of different ground motion parameter, different dynamic response laws of different slopes are appeared.